GlueX Start Counter Meeting, May 31, 2018

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GlueX Start Counter Meeting
Thursday, May 31, 2018
10:00 am EDT
CEBAF Center, Room L207
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the meeting on March 8
  3. Calibration and Efficiency
    1. Slides (Sean)
    2. Propagation time correction
  4. Time-dependent geometry adjustments
  5. NIM/TDR
  6. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2018 on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Mahmoud Kamel
  • FSU: Sean Dobbs
  • JLab: Thomas Britton, Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to authenticate.

Review of Minutes from the Previous Meeting

We went over the minutes from the meeting on March 8 without significant comment.

Calibration and Efficiency

Sean went over the state of things. See his slides] for plots and details.

We should nail down z-dependence of efficiency and resolution and complete the alignment studies we planned. Alignment parameters can be put into the geometry as perturbations to the nominal geometry. So far, only the CDC has done this. Sean showed a proposal for a parametrization of the perturbations. It was endorsed by the group.

Once the resolution is settled, he would also like to see the reconstruction report the errors on timing measurements.

He showed results from a prototype approach to getting time resolution as a function of z. He also showed results from the propagation time correction; there appears to be some systematic in the calibration scheme at the far end of the nose.

Lately there was some confusion about where the propagation time correction should go in the CCDB. That has been resolved now.